Does N### have its original engine?
You can ask that question, but don't be put off if the answer is "No". It's not uncommon for the previous owner(s) to simply trade in the original engine and got another freshly overhauled engine. Nothing wrong with that, unless you plan to restore the plane and want everything to be original.
I have a few suggested questions for you to ask the seller:
- How often was the plane flown? You don't want a hangar queen.
- How many hours were flown last year? By how many different pilots?
- Was the plane tied down outside or hangared?